Wood Flooring - Do I need to replace?

Hello - we have been living in our current house for almost 3 years, but in the last 6 months it appears that the wood floors throughout the house are having some issues (two levels - dining room and bedrooms in a split level house). They are gapping, cracks throughout planks, squeeking, feeling unstable when walking upon, and actually feel like they are moving.

We are also experiencing some border, trim, and drywall cracking in some spots in the dining room, and unsure if they are related. The house was inspected, and in great shape when we bought it. No water damage, and water has not been used on these floors. The only humidity issue was some water in the basement on two occassions (we use a humidifier there), and in the summer we had a solar attic fan installed above our dining room since our A/C was struggling to cool the house down on a hot sunny day (we were told upon inspection 2.5 ago to get an attic fan because moisture was collecting in the attic crawl space). These are the only two issues I can see as being moisture related.

Does it look like these floors will need to be replaced? Is there anything we can be doing to stop this from happening? This seems to be every foot or so, in each room that has the wood floors. It does not appear to be isolated. Sorry if this seems like I don't know what I am talking about - I don't (first time home owner). Thank you in advance for any pointers or advice you can provide.